Description: Kinematic and diabatic vertical velocity climatologies from a chemistry climate model

This title appears in the Scientific Report : 2016

Kinematic and diabatic vertical velocity climatologies from a chemistry climate model

The representation of vertical velocity in chemistry climate models is a key element for the representation of the large-scale Brewer–Dobson circulation in the stratosphere. Here, we diagnose and compare the kinematic and diabatic vertical velocities in the ECHAM/Modular Earth Submodel System (MESSy...

Personal Name(s):	Hoppe, Charlotte (Corresponding author)
	Ploeger, Felix / Konopka, Paul / Müller, Rolf
Contributing Institute:	Stratosphäre; IEK-7 JARA - HPC; JARA-HPC
Published in:	Atmospheric chemistry and physics, 16 (2016) 10, S. 6223 - 6239
Imprint:	Katlenburg-Lindau EGU 2016
DOI:	10.5194/acp-16-6223-2016
Document Type:	Journal Article
Research Program:	Chemisches Lagrangesches Modell der Stratosphäre (CLaMS) Composition and dynamics of the upper troposphere and middle atmosphere
Link:	OpenAccess OpenAccess
	Publikationsportal JuSER

Please use the identifier: http://hdl.handle.net/2128/12808 in citations.
Please use the identifier: http://dx.doi.org/10.5194/acp-16-6223-2016 in citations.

The representation of vertical velocity in chemistry climate models is a key element for the representation of the large-scale Brewer–Dobson circulation in the stratosphere. Here, we diagnose and compare the kinematic and diabatic vertical velocities in the ECHAM/Modular Earth Submodel System (MESSy) Atmospheric Chemistry (EMAC) model. The calculation of kinematic vertical velocity is based on the continuity equation, whereas diabatic vertical velocity is computed using diabatic heating rates. Annual and monthly zonal mean climatologies of vertical velocity from a 10-year simulation are provided for both kinematic and diabatic vertical velocity representations. In general, both vertical velocity patterns show the main features of the stratospheric circulation, namely, upwelling at low latitudes and downwelling at high latitudes. The main difference in the vertical velocity pattern is a more uniform structure for diabatic and a noisier structure for kinematic vertical velocity. Diabatic vertical velocities show higher absolute values both in the upwelling branch in the inner tropics and in the downwelling regions in the polar vortices. Further, there is a latitudinal shift of the tropical upwelling branch in boreal summer between the two vertical velocity representations with the tropical upwelling region in the diabatic representation shifted southward compared to the kinematic case. Furthermore, we present mean age of air climatologies from two transport schemes in EMAC using these different vertical velocities and analyze the impact of residual circulation and mixing processes on the age of air. The age of air distributions show a hemispheric difference pattern in the stratosphere with younger air in the Southern Hemisphere and older air in the Northern Hemisphere using the transport scheme with diabatic vertical velocities. Further, the age of air climatology from the transport scheme using diabatic vertical velocities shows a younger mean age of air in the inner tropical upwelling branch and an older mean age in the extratropical tropopause region.